The control of damage caused by wild and domestic animals is an ongoing challenge. The magnitude of the problem is indicated by the many types of devices and methods that have been used in attempts to control animal behavior and to keep them out of certain areas.
Most types of animal deterrent devices are ineffective because animals soon learn to ignore what does not harm them. Conversely, it has been shown that animals learn immediately to avoid areas where they have been harmed. For this reason, repelling and training devices which deliver an electric shock have proven to be very effective in altering animal behavior, and the use of shock producing devices results in immediate retreat and long term avoidance behaviors.
Electric animal repelling and training devices have been described with various power systems. A shocking device powered by the spark plug of a gasoline engine is shown by Dierking, U.S. Pat. No. 2,579,178 (1951). Devices such as shown by U.S. Pat. No. 4,153,009 to Boyle (1979), and U.S. Pat. No. 4,630,571 to Palmer (1986) use power directly from batteries. Other devices such as U.S. Pat. No. 922,377 to Ames (1909), French Patent 440,270 to Calvert (1912), Swiss Patent 82,560 to Baumann (1919), U.S. Pat. No. 4,476,810 to Heras (1984), and U.S. Pat. No. 5,095,646 to Bunkers (1992) use a continuous pulsating direct current or a battery and a converter. Modern fence charging devices are shown by U.S. Pat. No. 3,900,770 to Kaufman (1975), U.S. Pat. No. 4,394,583 to Standing (1983), U.S. Pat. No. 5,381,298 to Shaw (1995) and U.S. Pat. No. 5,514,919 to Walley (1996) which use various electronic circuits to produce a pulsating charge. While some modern fence charging devices use a capacitor to stabilize or to increase the output of the devices, none of these devices suggest using a capacitor alone as the energy storage mechanism of the device.
U.S. Pat. No. 5,894,818 to Betzen (1999) describes a baited animal repelling and training device in which the deterrent voltage that is maintained across the electrodes is stored in a capacitor. The innovation of using a capacitor to store the deterrent energy in a baited animal control device as described by Betzen (1999) allowed the creation of a small, easily portable, wireless device which delivers a single pulse of high voltage energy with a very low amperage, a very short discharge time and a short current path through the target pest animal attracted to the bait used on the device.
The situations and the species involved in animal control are widely varied and in many applications for an animal deterrent device it would be counterproductive to apply additional attractant to the area, thus rendering the device as described by Betzen (1999) less useful in these applications. In these cases the target pest animals are drawn to contact the deterrent device by their seeking shelter, garbage or other attractants incidental to the area.
Animal deterrents are required for such diverse situations as to keep marauding squirrels from bird feeders, to train cats to stay off of countertops, to scare rabbits out of flower beds, to prevent birds from perching in barns, to discourage pets from sleeping on furniture, or to eliminate dogs or racoons from garbage cans. Using a deterrent device that incorporated additional bait or attractant in these situations would be undesirable. Any additional attractant added to these situations would compound the problem by attracting even more pest animals to the area.